<template>
  <div class='xtx-carousel'>
    <ul class="carousel-body">
      <li v-for="(item,index) in imgList" :key="index" class="carousel-item " :class="{'fade':index ===ind}">
        <RouterLink to="/">
          <img :src="item.imgUrl" alt="">
        </RouterLink>
      </li>
    </ul>
    <a  @mouseenter="stop"  @mouseleave="start" @click="indSub" href="javascript:;" class="carousel-btn prev"><i class="iconfont icon-angle-left">⬅️</i></a>
    <a  @mouseenter="stop"  @mouseleave="start" @click="indAdd" href="javascript:;" class="carousel-btn next"><i class="iconfont icon-angle-right">➡️</i></a>
    <div class="carousel-indicator">
      <span :class="{'active':index=== ind}" @mouseleave="start" @mouseenter="stop" @click="ind =index" v-for="(i,index) in lengths" :key="i"></span>
    </div>
  </div>
</template>

<script>
import { ref, onUnmounted, watch } from 'vue'
export default {
  name: 'XtxCarousel',
  props: {
    imgList: {
      type: Array,
      default: () => []
    }
  },

  setup (props) {
    // 谨慎判断 length 防止报错
    watch(() => props.imgList, (newVal) => {
      lengths.value = newVal.length
      // 启动自动轮播
      auto()
    })
    console.log(props.imgList.length)
    const lengths = ref(0)

    // 轮播图控制下标
    const ind = ref(0)

    // 右箭头按钮
    const indAdd = () => {
      if (ind.value >= lengths.value - 1) {
        ind.value = 0
        return
      }
      ind.value++
    }
    // 左箭头按钮
    const indSub = () => {
      if (ind.value <= 0) {
        ind.value = lengths.value
        return
      }
      ind.value--
    }
    // 自动轮播
    const timer = ref(null)
    const auto = () => {
      clearInterval(timer.value)
      timer.value = setInterval(() => {
        if (ind.value >= lengths.value - 1) {
          ind.value = 0
          console.log(ind.value)
          return
        }
        ind.value++
      }, 3000)
    }

    // 暂停轮播
    const stop = () => {
      if (timer.value) clearInterval(timer.value)
    }
    const start = () => {
      auto()
    }
    // 组件消耗，清理定时器
    onUnmounted(() => {
      if (timer.value) clearInterval(timer.value)
    })
    return { ind, indAdd, indSub, lengths, auto, stop, start }
  }
}
</script>
<style scoped lang="less">
.xtx-carousel{
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel{
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0,0,0,0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background:  #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0,0,0,.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev{
        left: 20px;
      }
      &.next{
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>
